Metal spray gun



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H. J. GILLILAND ETI'AL METAL SPRAY GUN May 2, 1961 Filed Sept. 17. 1959"iii: V

May 2, 1961 H. J. GILLILAND ET AL 2,932,480

METAL SPRAY GUN Filed Sept. 17, 1959 2 Sheets-Sheet 2 United StatesPatent METAL SPRAY GUN Harry J. Gilliland, Birmingham, and Donald W.Jones, Mount Clemens, Mich., assignors to General Motors Corporation,Detroit, Mich., a corporation of Delaware Filed Sept. 17, 1959, Ser. No.840,551

2 Claims. (Cl. 239-84) This invention relates to improvements in metalspray ns. Metal spray guns of the wire feeding, gas blast type aredevices in which a metal rod or wire is continuously fed into acombustion zone in which the metal is melted and thereafter expelledfrom the gun in finely divided form by means of a blast of air or othersuitable gas. A mixture of combustible and combustion supporting gasessuch as acetylene and air or oxygen, respectively, are fed into themelting zone through suitable jets or passages surrounding the feedingpath of the metal rod or wire. When the combustible mixture is ignited,it melts the wire or rod fed into the melting chamber. A stream of orother gas is forcibly directed against the molten metal at the tip ofthe metal rod or wire in a manner such that it impinges sharply againstthe tip to thereby blast the molten metal into fine particles. Metalpowder spray guns are similar in construction and operation and differessentially in that a metal is delivered to the melting zone in the formof a gas propelled powder.

The nozzle construction of metal spray guns of this type usuallyincludes a burner tip which is provided with a wire feeding orificecentrally thereof and a plurality of burner jets substantiallysurrounding the longitudinal axis of the wire feeding orifice andpassing therethrough. It further includes an air cap enveloping theburner tip forming a combustion chamber between its inner walls and theburner tip and an air blast passage. The materials to be sprayed may befed into the melting zone either in the form of a rod or wire or in theform of a gas propelled powder as above indicated.

Heretofore in so far as it is known, metal spray guns of this type werecapable of directing the sprayed material in a generally single fixeddirection so that when used for spray coating of the inner surfaces of atubular member such as, for example, an engine cylinder, it wasnecessary to rotate the spray gun. Since the spray gun requires a numberof gas supplying conduits and a metal feeding means, the rotation of thespray gun involved diflicult manipulative problems.

It is the basic object of the present invention to provide a metal spraygun of the type described above which includes an air cap tipconstructed so as to direct the molten metal at an angle to the metalfeeding orifice which is rotatable with respect to the molten metalfeeding orifice and the burner jets whereby in operation of the spraygun the air cap tip is continuously rotated to direct the blast ofmolten metal continuously in a 360 are about the spray gun axis whileholding the spray' gun in a fixed position. It is a further object ofthe invention to provide a spray gun which includes means for rotatingthe air caps of a plurality of spray guns simultaneously whereby theinterior surfaces of a plurality of cylindrical surfaces such as thecylinders of an ,engine block may be simultaneously spray coated.

Further objects and advantages of the invention will be apparent fromthe following description, reference Patented May 2, 1961 being bad tothe accompanying drawings wherein a preferred embodiment of theinvention is shown.

In the drawings: Figure 1 is a top view of spray gun apparatus includingthree spray guns arranged abreast one another and operated by commondrive shafts to simultaneously spray I coat the walls of three cylindersof an engine block in accordance with the present invention;

Figure 2 is a cross-sectional view with parts broken away taken alongline 2-2 of Figure 5;

Figure 3 is a cross-sectional view taken along line 3-3 of Figure 5;

Figure 4 is a cross-sectional view with parts broken away taken alongline 44 of Figure 6;

Figure 5 is a cross-sectional view taken along line 55 of Figure l;

Figure 6 is an enlarged fragmentary cross-sectional view of the nozzleportion of the spray gun shown in Figure 5 Figure 7 is an enlargedfragmentary cross-sectional view of the gas feed portion of the spraygun shown in Figure 5.

In general as may be seen most clearly in Figure 5, the preferredembodiment of the spray gun of the present invention involves astationary burner tip 10, conduit means 12 for feeding a wire to theburner tip, conduit means 14 for feeding oxygen or air to the burnertip, conduit means 16 for feeding acetylene to the burner tip, and anair tip 18 disposed forwardly of the burner tip and enveloping theburner tip to form the combustion chamber 20 and adapted to direct themolten metal spray at an angle with respect to the longitudinal axis ofthe spray gun. A basic feature of the present invention is the provisionof a rotatable sleeve 22 which supports the air tip 18, envelops theburner tip 10 and forms an air passage to the combustion chamber 20between it and the burner tip'10. The sleeve 22 is rotatably mountedwithin the housing 24 by means of ball bearings 26 and 28 and has keyedthereto a gear 30 which is power driven by means of the pinion 32. Aswill be seen moreclearly hereinafter, the pinion 32 is preferablyconnected to the pinions of a plurality of spray guns whereby thesepinions may be driven simultaneously through a common drive shaft.

The sleeve 22 preferably consists of a hollow shaft portion 34 carriedby the bearings 26 and 28 press-fitted to the housing and rotatablysealed with respect to the housing by a resilient annular seal 36. Theshaft portion 34 is retained within the housing by the nut 38 threadedto the sleeve and engaging the bearing 26 through a washer. An extension40, threaded to the shaft portion 34, carries the air cap 18 pressfittedtherein.

Passing through the shaft portion 34 of the sleeve 22 are the wirefeeding conduit 12, the acetylene conduit 16 and the oxygen conduit 14which are attached on opposite ends to cylindrical adapters 42 and 44.As shown more clearly in Figure 7, the adapter 44 is held in the housingby means of the externally threaded nut 46 engaging the flange portion48 of the adapter. The adapter is provided with an acetylene passage 50in communication with the acetylene conduit 16,.which leads to thecircumferentially disposed groove 52 sealed with. respect to the housingby the elastomeric seals 54 and 60. Acetygroove 64, sealed with respectto the housing by the elastomeric seals 60 and 66, to which oxygen issupplied through the fitting 68.

the wire feeding conduit 12. As is shown in Figure 5,

'the apparatus includes a wire feeding mechanism includ- The adapteralso includes a V centrally disposed passage 70 in communication withing a drive roller 72 and a pressure roller 74. The pressure roller 74is supported on an adjustable housing portion 76 which in turn issupported for vertical move ment by the stud 78 and held in ahorizontally aligned position by a spring 80. The wire supply carried bythe reel 82 as shown in Figure 1 is fed through the spray gun by meansof the rollers 72 and 74 in an obvious manner. The degree of pressurebetween the rollers is controlled by a vertical adjustment of thepressure roller carrying member 76.

The adapter 42 which is spaced from the sleeve 22 to form a passagetherebetween includes an acetylene passage 84 in communication with theacetylene conduit 16 leading to an annular groove 86 in the endface ofthe adapter 42. Similarly, the adapter includes a passage 88 incommunication with the oxygen conduit 14 leading to the annular groove86. Adjacent the groove 86 is disposed an annular metering plate 90which includes an annular groove 92 in the face thereof. The plate 90 isfixed to a bushing 94 which is held in a counterbore of the wire feedingpassage 96 of the adapter. As shown in Figure 4, a plurality of openings98 are provided through the metering plate 90 which communicate betweenthe grooves 86 and 92.

The burner tip includes a centrally disposed wire feeding passage 100and a plurality of combustible gas feeding passages '102 disposedthereabout which converge about the passage 100 at the burner tip. Theburner tip is disposed against the metering plate 90 so that thecombustible gas feeding passages 102 are in alignment with the groove 92of the metering plate. As shown in Figure 4, the openings 98 through themetering plate are out of alignment with the combustible gas feedingpassages 102 of the burner tip to insure proper metering and mixing ofthe gases. The metering plate 90 and the burner tip 10 are secured inposition by a retainer 104 threaded to the adapter 42. Preferably themetering plate 90 is provided with a dowel (not shown) to insure that onassembly of the parts, the openings 98 and passages 102 are not aligned.

The air tip 18 is provided with conical interior walls spaced from theburner tip to provide the conical combustion chamber and an air passage106 between the burner tip and the air cap. A portion of the air cap iscut away as indicated by the numeral 107 and the inner surfaces 108 ofthe air cap 18 opposite the cut away portion 107 are curved inwardly soas to direct the sprayed molten metal at an angle of approximately 45with respect to the longitudinal axis of the spray gun. The air cap 18further includes an air passage 110 through which air is passed to coolthe air cap and an annular flange 112 which extends between a shoulder1-14 or" the burner tip and the retainer 104. The retainer 104 alsoincludes a plurality of openings 116 therethrough in advance of theflange 112 of the air cap.

It will thus be seen that rotatable sleeve 22 supports the air cap 18and forms air passages in combination with other internal elements ofthe spray gun mechanism. This air passage consists of the air pressurefitting 1 18 which leads to an annular space 47 between the nut 46 andshaft portion 34 of the rotatable sleeve 22. The annular space 47 leadsto the space 120 between the sleeve 22 and the conduits 12, 14 and 16and adapter 42 which in turn leads to an enlarged annular space 122 inthe region of the burner tip 10. An air conduit 124 leading to the wirefeeding conduit 96 is provided to equalize the pressure in the wirefeeding tube.

In operation of the spray gun, the wire is fed through the burner tip 10by means of the rollers 72 and 74. Acetylene, oxygen and air underpressure are admitted to the spray gun through the fittings 58, 68 and118, respectively. The oxygen and acetylene are mixed in the groove 86and metered as they pass through the metering plate 90 and are passedthrough the burner tip 10 so as to converge at a predetermined .pointforward of the burner tip. The compressed air passes through the annularspace 47, the space and into the annular space 122. From thence aportion of the air stream, guided by the air cap flange 112, is directedthrough the air cap passage 110. A major portion of the air passesinwardly of the flange 112 through the openings 116 of the retainer 104through the annular passage between the flange 112 and the burner tipshoulder 114, and through the conical passage 106 into the combustionchamber 20 wherein it is operative to atomize and propel the metalmelted by the burning gases out of the spray gun. The curved portion 108causes the molten metal spray to be propelled at an angle ofapproximately 45 to the longitudinal axis of the spray gun. Meanwhilethe sleeve 22 has been caused to rotate by application of power to thepinion 32 whereby the gun is caused to spray through a 360 are at a ratedepending on the speed at which the sleeve 22 is rotated.

Although the air cap 18 has been described in terms of a structure whichcauses the molten metal to be directed at an angle of approximately 45with respect to the longitudinal axis of the spray gun. It is obviousthat for the purposes of the present invention, it is essential onlythat the spray be directed at a sufiicient acute angle from thelongitudinal axis of the spray gun so that on rotating the air cap, itwill satisfactorily spray coat cylindrical walls disposed parallel tothe longitudinal axis of the gun.

As shown in Figure l, a plurality of spray guns are mounted abreast oneanother for the purpose of spray coating a plurality of cylindersurfaces of a cylinder block 1'25. The pinions 32 of each spray gun areinterconnected and the wire drive gears 72 of each spray gun aresimilarly interconnected. Preferably the spray guns are slidably mountedon rods 126 and reciprocably moved by hydraulic pistons 128 whereby theymay be moved simultaneously within cylinder bores at a predeterminedrate while in operation to spray coat the cylinder bore surfaces in anobvious manner.

While the embodiment of the present invention as disclosed hereinconstitutes a preferred form, it is to be understood that other formsmay be adopted without departing from the spirit of the invention.

We claim:

1. A spray gun assembly for use in simultaneously metal spraying thebores of a plurality of cylinders posi tioned in a plane, said assemblycomprising a carrier means adapted for reciprocable movement in saidplane, a plurality of spray guns mounted abreast of one another uponsaid carrier means whereby a reciprocating movement of said carriermeans is operative to move said spray guns reciprocably within saidbores, each of said spray guns comprising a burner tip provided with ametal feeding orifice and a multiple number of burner jets substantiallysurrounding the axis of said orifice, a housing, metal feeding conduitmeans attached to said housing in communication with said burner tiporifice, combustible gas conduit means secured to said housing and incommunication with said burner jets, an air cap surronndmg said burnertip forming a gas blast passage therebetween and adapted to direct ablast of gas between the molten metal formed at said burner tip, saidair cap being adapted to direct the molten metal spray at an acute anglew1th respect to the longitudinal axis of said spray gun, a sleevesurrounding said conduits supporting said air cap and rotatably mountedon said housing, said sleeve being spaced from said conduits androtatably sealed with respect to said housing to provide a gas passagetherebetween in communication with said gas blast passage, a ring gearfixed to said sleeve, a pinion operatively mounted within said housingconnected to said ring gear, means for supplying a compressed gasthrough said housing to said gas passage, rotatable drive means forfeeding a Wire through said metal feeding .conduit, meansinterconnecting the said pinions of each wire feeding means are adaptedto be simultaneously driven by a single drive means.

2. A spray gun assembly for use in simultaneously metal spraying thebores of a plurality of cylinders positioned in a plane, said assemblycomprising a carrier means adapted for reciprocable movement in saidplane, a plurality of spray guns mounted abreast of one another uponsaid carrier means whereby a reciprocating movement of said carriermeans is operative to move said spray guns reciprocably within saidbores, each of said spray guns comprising a burner tip provided with ametal feeding orifice and a multiple number of burner jets substantiallysurrounding the axis of said orifice, a housing, metal feeding conduitmeans attached to said housing in communication with said burner tiporifice, combustible gas conduit means secured to said housing and incomrespect to the longitudinal axis of said spray gun, a sleevesurrounding said conduits supporting said air cap and rotatably mountedon said housing, said sleeve being spaced from said conduits androtatably sealed with respect to said housing to provide a gas passagetherebetween in communication with said gas blast passage, a ring gearfixed to said sleeve, a pinion rotatably mounted within said housingoperatively connected to said ring gear, means for supplying acompressed gas through said housing to said gas passage, means forfeeding a metal through said metal feeding conduit, meansinterconnecting the said pinions of each of said spray guns in analigned relation whereby each of said pinions are adapted to be drivensimultaneously by a single drive means and means for simultaneouslyoperating each of said metal feeding means.

References Cited in the file of this patent UNITED STATES PATENTS SwedenNov. 20, 1923

